Vulnerability-Lookup

GHSA-FM5X-5PXQ-6229

Vulnerability from github – Published: 2026-01-15 21:31 – Updated: 2026-01-15 21:31

Details

When telemetry collectors are frequently subscribing and unsubscribing to sensors continuously over a long period of time, telemetry-capable processes like chassisd, rpd or mib2d will crash and restart, which - depending on the process - can cause a complete outage until the system has recovered.

This issue affects:

Junos OS:

all versions before 22.4R3-S8,
23.2 versions before 23.2R2-S5,
23.4 versions before 23.4R2;

Junos OS Evolved:

all versions before 22.4R3-S8-EVO,
23.2 versions before 23.2R2-S5-EVO,
23.4 versions before 23.4R2-EVO.

Severity

6.5 (Medium)


                  
                    CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

7.1 (High)


                  
                    CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/AU:Y/R:A/RE:M

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JSON

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{
  "affected": [],
  "aliases": [
    "CVE-2026-21921"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-416"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-01-15T21:16:08Z",
    "severity": "HIGH"
  },
  "details": "A Use After Free vulnerability in the chassis daemon (chassisd) of Juniper Networks Junos OS and Junos OS Evolved allows a network-based attacker authenticated with low privileges to cause a Denial-of-Service (DoS).\n\nWhen telemetry collectors are frequently subscribing and unsubscribing to sensors continuously over a long period of time, telemetry-capable processes like chassisd, rpd or mib2d will crash and restart, which - depending on the process - can cause a complete outage until the system has recovered.\n\nThis issue affects:\n\n\u00a0Junos OS:\u00a0\n\n\n\n  *  all versions before 22.4R3-S8,\n  *  23.2 versions before 23.2R2-S5,\n  *  23.4 versions before 23.4R2;\n\n\n\n\nJunos OS Evolved:\n\n\n\n  *  all versions before 22.4R3-S8-EVO,\n  *  23.2 versions before 23.2R2-S5-EVO,\n  *  23.4 versions before 23.4R2-EVO.",
  "id": "GHSA-fm5x-5pxq-6229",
  "modified": "2026-01-15T21:31:48Z",
  "published": "2026-01-15T21:31:48Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-21921"
    },
    {
      "type": "WEB",
      "url": "https://kb.juniper.net/JSA106021"
    },
    {
      "type": "WEB",
      "url": "https://supportportal.juniper.net/JSA106021"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:Y/R:A/V:X/RE:M/U:X",
      "type": "CVSS_V4"
    }
  ]
}

CVE-2026-21921 (GCVE-0-2026-21921)

Vulnerability from cvelistv5 – Published: 2026-01-15 20:28 – Updated: 2026-01-15 20:55

Title

Junos OS and Junos OS Evolved: When telemetry collectors are frequently subscribing and unsubscribing to sensors chassisd or rpd will crash

Summary

A Use After Free vulnerability in the chassis daemon (chassisd) of Juniper Networks Junos OS and Junos OS Evolved allows a network-based attacker authenticated with low privileges to cause a Denial-of-Service (DoS). When telemetry collectors are frequently subscribing and unsubscribing to sensors continuously over a long period of time, telemetry-capable processes like chassisd, rpd or mib2d will crash and restart, which - depending on the process - can cause a complete outage until the system has recovered. This issue affects: Junos OS: * all versions before 22.4R3-S8, * 23.2 versions before 23.2R2-S5, * 23.4 versions before 23.4R2; Junos OS Evolved: * all versions before 22.4R3-S8-EVO, * 23.2 versions before 23.2R2-S5-EVO, * 23.4 versions before 23.4R2-EVO.

Severity

6.5 (Medium)


                        
                          CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

7.1 (High)


                        
                          CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/AU:Y/R:A/RE:M

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-01-15 20:54 UTC

CWE

CWE-416 - Use After Free

Assigner

juniper mitre root Scorecard

References

2 references

URL	Tags
https://supportportal.juniper.net/JSA106021	vendor-advisory
https://kb.juniper.net/JSA106021	vendor-advisory

Impacted products

2 products

Vendor	Product	Version
Juniper Networks	Junos OS	Affected: 0 , < 22.4R3-S8 (semver) Affected: 23.2 , < 23.2R2-S5 (semver) Affected: 23.4 , < 23.4R2 (semver)
Juniper Networks	Junos OS Evolved	Affected: 0 , < 22.4R3-S8-EVO (semver) Affected: 23.2 , < 23.2R2-S5-EVO (semver) Affected: 23.4 , < 23.4R2-EVO (semver)

Date Public

2026-01-14 17:00

Show details on NVD website

JSON

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{
  "containers": {
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        "metrics": [
          {
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                "id": "CVE-2026-21921",
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                  },
                  {
                    "Technical Impact": "partial"
                  }
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                "role": "CISA Coordinator",
                "timestamp": "2026-01-15T20:54:58.001808Z",
                "version": "2.0.3"
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          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
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          "product": "Junos OS Evolved",
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              "status": "affected",
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Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

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GHSA-FM5X-5PXQ-6229

CVE-2026-21921 (GCVE-0-2026-21921)

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